The present invention relates to flow control and filtration methods and apparatuses relating to medical devices, drug delivery devices, food dispensing devices, aerosol generation devices and the like.
Liquid atomizers are well known and come in several types, including aerosol, manual and ultrasonic. For example, there are aerosol atomizers for various applications, such as dispensing cosmetic and hygienic products (hair spray, deodorant, etc.) and cleaning solutions (disinfectants, air fresheners, etc.). Aerosol atomizers can also be used for dispensing medicaments although they have significant drawbacks when used for that purpose.
Ultrasonic atomizers include one type using a piezoelectric element to atomize a liquid medicament deposited thereon by manually moving a piston within a cylinder containing the medicament to be atomized. The piston forces the liquid from an outlet in the cylinder, which deposits it onto the piezoelectric atomizer, which in turn is activated as part of the manual medicament-dispensing operation.
These existing drug delivery systems, however, suffer from a number of disadvantages. One problem with existing drug delivery systems is poor delivery efficiency of the medication. It has been estimated that on average, with existing systems, only a small percentage of the medication dose which is dispensed from a fluid reservoir actually reaches the patient""s lungs where it can achieve the intended result. A significant portion of the medication impacts and sticks to the inner surfaces of the device. This makes the drug delivery device less than optimal for delivering expensive medication.
Thus, there exists the need for an apparatus and/or method of improving the delivery efficiency of fluid delivery devices.
The present invention presents new and unique methods and apparatuses for creating a directional and entraining airflow over an aerosol generation surface and the internal walls of an exhaust (mouth) piece for a fluid dispensing device.
The present invention also presents methods and apparatuses for directing air flow through a filtration element to limit aerosol particle size. Thus, particle size distribution tailored to a particular size or range of sizes of particles.
The present invention is illustrated and described in conjunction with a nebulizer/inhalable drug delivery system. Such systems encompass dry powder generators, nebulizers (liquid generators), propellent generators, and the like.
Accordingly, in one aspect of the present invention, an exhaust member for an airflow control apparatus is presented. The airflow control apparatus includes a aerosol generation surface and a material dispensing member positioned adjacent thereto. The exhaust member includes a generally circular housing having an inner wall, a first end positioned adjacent the aerosol generation surface of the airflow control apparatus, an opening for exhausting a material entrained airflow out of the exhaust member, a plurality of inlets in communication with ambient air and an inner shroud positioned adjacent the inner wall establishing a gap therebetween. The shroud includes a central opening adjacent the aerosol generation surface.
In another aspect of the present invention, a method for delivering an aerosolized material from an exhaust ember of an airflow control apparatus includes the steps of discharging an amount of a material on an aerosol generation surface of the airflow control apparatus, where the aerosol generation surface is positioned adjacent a substantially closed end of the exhaust member of the apparatus. The method also includes the steps of aerosolizing the material via the aerosol generation surface, concurrently creating a first airflow for sweeping over the aerosol generation surface to entrain the aerosolized material, and a second airflow creating a layer of air between the first airflow and walls of the exhaust member. The method also includes the step of combining the first and the second airflows downstream from the aerosol generating surface.
In yet another aspect of the present invention, a method for delivering a dose of an aerosolized medicament from an exhaust member of a drug delivery device having an aerosol generation surface includes the steps of discharging a dose of a medicament on the aerosol generation surface of the drug delivery device, where the aerosol generation surface is positioned adjacent a substantially closed end of the exhaust member, aerosolizing the material via the aerosol generation surface, concurrently creating a first airflow for sweeping over the aerosol generation surface to entrain the aerosolized medicament, and a second airflow creating a layer of air between the first airflow and walls of the exhaust member, and combining the first and the second airflows downstream from the aerosol generating surface.
In yet another aspect of the present invention, a system for delivering an aerosolized material from an exhaust member of an airflow control apparatus includes discharging means for discharging an amount of a material, aerosolizing means for aerosolizing a material, where the discharging means discharges the material adjacent to the aerosolizing means, airflow generating means for concurrently creating a first airflow for sweeping over the aerosolizing means to entrain aerosolized material, and a second airflow creating a layer of air between the first airflow and walls of the exhaust member, and combining means for combining the first and the second airflows downstream from the aerosol generating surface.
A three-dimensional object may be used with the aspects of the present invention by placing it within a path of an entrained airflow prior to the airflow exiting through the opening. The three-dimensional objects may include a cylindrical shape, a circular, ellipsoidal or hemispherical shape, a planer shape, an interlocking mesh, and a cylindrical array.
The three-dimensional shape may also include a porous media. Such a porous media may establish a predetermined particle size based upon properties of the porous media. Such properties include at least one of a thickness of the media, a pore volume of the media, a pore size of the media and a hydrophillic/hydrophobic balance of the media.
The gap established between the shroud and the inner wall of the previous aspect may also be adjustable.